1. Field of the Invention
Thermally and oxidatively stable resins are finding increasingly widespread utility in the fabrication of composites for military and non-military applications. Polymers containing triazine ring systems and triazine groups offer a promise of increased thermal stability and good mechanical characteristics. However, these polymers have been limited in their usefulness from a practical point of view because of processing and curing difficulties. This invention overcomes most, if not all, of the disadvantages associated with the use of polymers containing triazine ring systems to form curable resins.
2. Description of the Prior Art
The triazine ring system is well known in the field of organic chemistry. Triazine compounds have been used for herbicides and numerous other applications. Both symmetrical triazine (s-triazine) and asymmetrical triazine (as-triazine) polymers have been prepared. However, unlike the approach described for the present invention, these materials do not have a preformed triazine ring system. The ring system of these prior art polymers are formed during the polymerization reaction. Thus, in both cases the method of preparation and the consequent processing characteristics are much more complex than that of this invention. Further, asymmetrical triazine polymers prepared via prior art methods are not thermosetting and therefore are not useful in the fabrication of thermoset composites; see, e.g., "Acetylene Terminated Phenyl-As-Triazine Oligomers and Polymers Therefrom" by P. M. Hergenrother, Organic Coatings and Plastic Chemistry, Vol. 38, page 576 (March 1978).
Thus, there is still a need for polymerizable s-triazine oligomers which exhibit good processing characteristics, and which are flexible and curable into thermoset polymers or resins.